Then, when our kids became old enough to move around town on their own, we got them cell phones so they could stay in touch. And the way kids stay in touch is through text messaging, not voice. A family SMS plan was added.

Today, several days can go by when I don’t use the voice feature on my iPhone 4. I stay in communication with my family primarily via text and email. Data-based communications are faster, more convenient and less intrusive.

But according to this story in the Wall Street Journal, traditional text messaging may be headed the way of voice calls. The explosive growth that SMS services have enjoyed in the last decade has slowed, and new services on the horizon could cut into a very profitable business for the telcos.

While U.S. cellphone users sent and received more than 1 trillion texts in the second half of 2010, according to CTIA, a wireless industry trade group, that was just an 8.7% increase from the prior six months. It was the slimmest gain since texting exploded last decade.

Text traffic will come under more pressure in the months ahead. This week, Apple Inc. showed off an application that will allow iPhone and iPad owners to bypass carriers and send text messages over the Internet to other people with Apple devices.

Google Inc., whose Android software is the most popular operating system on smartphones, has also recently worked on a messaging application, a person familiar with the matter said.

The new messaging tools—answers to Research In Motion Ltd.’s popular BlackBerry Messenger—are a growing threat to a texting business that generated $25 billion in...